2 consumer units

[ulluullu]

I am in the middle of a new build house construction (bungalow) where the runs from the main consumer unit (if there is only 1)
will be in some cases nearly 60 meters of cable. So i was thinking, that it might be smarter to put a second consumer unit at
the other end of the house and run a *big* cable over to it from the supply, rather than running so many expensive long cables
for individual circuits. What i've read about is about installing a garage... but i'm thinking something a little heavier duty,
1/2 a house.

If anyone has any advise and thoughts about this, please.

To the same structure, i am installing the conductors for a lightning protection system, These are equipotentially bonded
to the steel structure, the rebar and about 10 tons of structural steel fixed to the bedrock. Would you connect the house
ground to the lightning protection ground? Or would you try to put a separate ground in for the house that would not spike
when the structure is being zapped by lightning? The building is on an exposed location in the inner hebridies, where it is
the highest point for miles - hence the LPS. In this regard, i am preparing to run a portion of the house electrics
using an inverter and renewable energy batteries as a lighting isolated electrical system; how would you establish the earth
for this subsystem (another separate earthing point?). How would you protect from lightning when you expect the house
to be struck once every 2 years?

 

[Octopus]

Are you a sparky?

 

[Specialist]

Are you a sparky?

Fair question.

 

[Geordie Spark]

This must be a Hell of a big bungalow !!! :uhoh2:

It reminds me of a Self Build I was involved in a couple of years ago. It was a VERY large 4 bed detached & the owner / builder was considering fitting 2 boilers for the heating !!!

In the event, he was persuaded that one 37kW (gas combi) was more than adequate & this was proved to be true.

On the electrical side, the CU for the house was an 18 way with an assortment of RCDs, MCBs & a few RCBOs for good measure. The 2 car garage with workshop had its own 5 way board with 100A main switch & 4 RCBOs which left 1 spare way.

 

[Octopus]

Are you in the UK?

 

[ulluullu]

Yes its big precisely 280m2 - the grand-designs sort of architecture prevents wiring passing through the heart of the
building - as it has a flat roof, there is no attic for services to run, so wires must all run the long way limited
by the room layout; I'm an electrical engineer /computer engineer.

 

[morph]

Are you in the UK?

well it does say the Hebridies in the post

 

[Guest123]

Are you in the UK?

Inner Hebridies apparently.

 

[Guest123]

Can we please keep replies on topic

Thank you.

 

[Geordie Spark]

Can we please keep replies on topic

Thank you.

Ok .......... soz Lenny.

Divvent bannis ..... aahm a Geordieman!!!!

 

[Engineer54]

I am in the middle of a new build house construction (bungalow) where the runs from the main consumer unit (if there is only 1)
will be in some cases nearly 60 meters of cable. So i was thinking, that it might be smarter to put a second consumer unit at
the other end of the house and run a *big* cable over to it from the supply, rather than running so many expensive long cables
for individual circuits. What i've read about is about installing a garage... but i'm thinking something a little heavier duty,
1/2 a house.

If anyone has any advise and thoughts about this, please.

To the same structure, i am installing the conductors for a lightning protection system, These are equipotentially bonded
to the steel structure, the rebar and about 10 tons of structural steel fixed to the bedrock. Would you connect the house
ground to the lightning protection ground? Or would you try to put a separate ground in for the house that would not spike
when the structure is being zapped by lightning? The building is on an exposed location in the inner hebridies, where it is
the highest point for miles - hence the LPS. In this regard, i am preparing to run a portion of the house electrics
using an inverter and renewable energy batteries as a lighting isolated electrical system; how would you establish the earth
for this subsystem (another separate earthing point?). How would you protect from lightning when you expect the house
to be struck once every 2 years?

1/. Where are you running the cables, in the screed via PVC conduits and single conductors ??

2/. 280sq m isn't exactly that big, but for a bungalow it's a good size. As for dual CU's i've never liked the idea in a domestic installation. Better to look for a position around the centre of the house if your worried about long cable runs.

3/. Yon Have to bond the LP system to the general supply MET it's a regulation. Personally, if this is a structural steel building i'm not too sure i would use the steelwork as your down conductor for the LP. I would be more inclined to use that and the heavy foundation work as my house grounding and create a separate grounding system and down conductors for the lightning protection system. ....I'm assuming that the house will be using a TT earthing system, because of it's remoteness.

4/. The LP system should if installed correctly protect renewable energy system, not quite sure what you mean by isolated electrical system ...give more information...

 

[Des 56]

in some cases nearly 60 meters of cable. So i was thinking, that it might be smarter to put a second consumer unit at ​the other end of the house and run a *big* cable over to it from the supply, rather than running so many expensive long cables

I would say your getting warmb

Expensive, ( tut tut,thats a secondary isssue, if at all)

What i've read about is about installing a garage... but i'm thinking something a little heavier duty,

Your thinking may need expansion on this idea,but i suspect you are thinking along the right lines and getting warmer

 

[Engineer54]

Thinking about your LP system a little more, .... If you contact ''Furse'' they do a free design service for customers. This would be a prudent move on your part, as it would be difficult to walk you through the do's and dont's on a forum. I've a friend in Cyprus that used this service on a large showroom building and the information, part numbers and drawing they provided were easy to follow and not over designed to increase sales of materials.

Give them call, well worth it from my experience!!

 

[PC Electrics]

There's nowt wrong with the basic idea of using two CUs to keep circuit lengths down. The primary criteria though are volt drop, disconnection times and loading, not cost. The main CU could be a 2RCD hi integrity unit with one of the unprotected ways feeding a distribution circuit to a 2RCD unit on the other side of the house.

You really need an electrician to look at the number of circuits, loading and circuit lengths etc etc so he can calculate cable sizes and runs and divvy it all up in a sensible fashion. You'll also need to know where the service head is going to be.

As with all things, there are many ways to skin a cat. so get someone in who knows what they are doing. You need someone with design skills not just an installation monkey.

 

[Engineer54]

Typical, ....The OP asks a multitude of questions, then buggers off when you ask for clarification on a couple/few points!!!!